Process for producing thermoplastic resin

Abstract

A process for producing a thermoplastic resin which comprises graft-polymerizing at least one vinyl monomer (IV) onto a modified polyorganosiloxane (III) obtained by condensation of from 90 to 99.8% by weight of an organosiloxane (I) having a structural unit represented by the formula R 1 n SiO.sub.(4-n)/2, wherein R 1 represents a substituted or unsubstituted monovalent hydrocarbon group and n is an integer of from 0 to 3, and from 10 to 0.2% by weight of a graft crosslinking agent (II) having a modified alkoxysilane structure.

What is claimed is: 
     
       1. A process for producing a thermoplastic resin which comprises graft-polymerizing at least one vinyl monomer (IV) onto a modified polyorganosiloxane (III) obtained by condensation of from 90 to 99.8% by weight of an organosiloxane (I) having a structural unit represented by the formula R 1   n  SiO.sub.(4-n)/2, wherein R 1  represents a hydrocarbon group, phenyl group or hydrocarbon group substituted by halogen or a cyano group and n is an integer of from 0 to 3, and from 10 to 0.2% by weight of a graft crosslinking agent (II) containing an alkoxysilane structure and having an azo group or disulfide group, the sum of said organosiloxane (I) and said graft crosslinking agent (II) being 100% by weight. 
     
     
       2. A process as claimed in claim 1, wherein said graft crosslinking agent (II) contains an alkoxysilane structure and has an azo group. 
     
     
       3. A process as claimed in claim 1, wherein said graft crosslinking agent (II) is at least one member selected from the group consisting of 2-azoisobutyronitrile-2-cyanopropylmethyldimethoxysilane and 2-(trimethyl-thiuram disulfied)ethylmethyldimethozysilane. 
     
     
       4. A process as claimed in claim 1, wherein said organosiloxane (I) is at least one member selected from the group consisting of hexamethylcyclotrisiloxane, octamethyl-cyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and trimethyltriphenylcyclotrisiloxane. 
     
     
       5. A process as claimed in claim 1, wherein the amount of said graft crosslinking agent (II) is from 0.5 to 5% by weight. 
     
     
       6. A process as claimed in claim 1, wherein said vinyl monomer (IV) is at least one member selected from the group consisting of an aromatic alkenyl compound, a methacrylic ester, an acrylic ester, a vinyl cyanide compound, an olefin, a conjugated diene, acrylic acid, methacrylic acid, a maleimide compound, and maleic anhydride. 
     
     
       7. A process as claimed in claim 1, wherein said vinyl monomer (IV) comprises from 65 to 75% by weight of styrene and from 25 to 35% by weight of acrylonitrile. 
     
     
       8. A process as claimed in claim 1, wherein the amount of said modified polyorganosiloxane (III) is from 5 to 80% by weight and the amount of said vinyl monomer (IV) is from 95 to 20% by weight, the sum of (III) and (IV) being 100%. 
     
     
       9. A process as claimed in claim 8, wherein the amount of said modified polyorganosiloxane (III) is from 10 to 60% by weight and the amount of said vinyl monomer (IV) is from 90 to 40% by weight. 
     
     
       10. A process as claimed in claim 1, wherein the thermoplastic resin has a graft ratio of 80% by weight or more. 
     
     
       11. A process as claimed in claim 1, wherein the thermoplastic resin has an intrinsic viscosity as measured in methyl ethyl ketone of from 0.2 to 0.8.